1. Field of the Invention
The present invention relates in general to an integrated circuit, and more particularly to an integrated circuit for a high-side transistor driver.
2. Description of the Prior Art
A variety of power supplies and motor drivers utilize the bridge circuits to control a power source to the load. The bridge circuit normally has a high side transistor connected to the power source and a low side transistor connected to the ground. A common node between the high side transistor and the low-side transistor is coupled to the load. As transistors are controlled to alternately conduct, the voltage of the common node swings in between the power source and the ground. Therefore the control of a high-side transistor driver requires a charge pump circuit and/or a floating drive circuit in order to fully turn on the high-side transistor. In recent development, many floating circuits are being disclosed in U.S. Pat. No. 6,344,959 (Milazzo), U.S. Pat. No. 6,781,422 (Yang) and U.S. Pat. No. 6,836,173 (Yang).
FIG. 1 shows a high-side transistor drive circuit. A floating circuit 10 is applied to control the on/off of the high-side transistor 20. A feeding capacitor 15 is connected to send the control signal S1 from a low-voltage inverter 16 to the floating circuit 10. A charge-pump capacitor 40 provides a supply voltage to the floating circuit 10. A voltage VD charges the charge-pump capacitor 40 through a diode 45 once the low-side transistor 30 is switched on. The ground reference of the charge-pump capacitor 40 is pulled to the level of the voltage source VIN when the high-side transistor 20 is turned on.